1. Field of the Invention
The present invention relates to an eye fundus camera for photographing and recording an image of a subject""s eye in a hospital of ophthalmology or the like. More particularly, this invention is concerned with an eye fundus camera suitable for fluorescence contrast photography.
2. Description of the Related Art
For performing fluorescence contrast photography using an eye fundus camera, a fluorescein that fluoresces in response to excitation light of specified wavelengths is intravenously injected into a patient. The fundus of the patient""s eye is illuminated with the excitation light, and the fluorescent fundus is photographed. Indocyanine green or the like is employed as the fluorescein in infrared fluorescence photography in which infrared light that is invisible light is adopted as the excitation light.
FIG. 9 shows a typical configuration of a conventional eye fundus camera capable of performing infrared fluorescence photography. Since infrared light is utilized, an infrared television camera is used for observation or recording. A patient lying near a base 1 wears a face holder 2. A fixation lamp 3 is mounted on the face holder 2. A stage 4 whose position is adjustable back and forth, right and left, and up and down is placed on the top of the base 1. A housing 6 for accommodating an optical system composed of optical elements including an exciter filter 5 for infrared fluorescence designed for eye fundus cameras, and an operator stick having a position adjustment lever 7 and a photography switch 8 are mounted on the stage 4. A 35-mm film camera 9, an optical finder 10, and a relay lens unit 12 are fixed to the housing 6. The 35-mm film camera 9 is employed in color photography or visible-light fluorescence photography. An operator observes a fundus with the naked eyes through the optical finder 10. The relay lens unit 12 includes a barrier filter 11 used for infrared-fluorescence recording and enables mounting of a television camera. An infrared television camera 15 used for observation can be mounted on the optical finder 10 via a relay lens unit 14 that enables mounting of a television camera and includes a barrier filter 13 used for infrared-fluorescence observation. An output of the television camera 15 is fed to an observation display 16 over a cable. On the other hand, an infrared television camera 17 used for recording is mounted on the relay lens unit 12. An output of the television camera 17 is fed to an image recording device 18 and a display 19 used to display a record image over a cable.
The foregoing conventional eye fundus camera has an optical path defined independently for observation and recording alike. Therefore, the relay lens unit 14 for observation, infrared television camera 15 for observation, and display 16 for displaying a view image must be arranged along an optical path different from an optical path along which the relay lens unit 12 for recording, infrared television camera 17 for recording, and display 19 for displaying a record image are arranged. This leads to a complex structure and a large number of parts, and poses a problem in that the eye fundus camera becomes large in size and expensive.
Moreover, the infrared television camera 15 is connected to the optical finder 10 via the relay lens unit 14 in order to produce a view image seen through the optical finder 10. When an operator sees through the optical finder 10 for color photography or visible-light fluorescent photography, the operator must dismount the relay lens unit 14. Moreover, the cable extending from the infrared television camera 15 mounted on the relay lend unit 14 can get entangled and thus interfere with the manipulation of the eye fundus camera. These factors pose a problem in that they hinder improvement in maneuverability of the eye fundus camera.
Accordingly, an object of the present invention is to solve the foregoing problems and to provide an eye fundus camera that is compact and low-cost and offers excellent maneuverability. According to one aspect, the present invention that achieves at least one of these objectives relates to an eye fundus camera comprising an illumination optical system configured to illuminate the fundus of a patient""s eye with light of wavelengths falling within a first wavelength band, and a photography optical system configured and positioned to form an image of the fundus illuminated by the illumination optical system so that a fundus image will be produced by the camera. The photography optical system includes a first filter that exhibits a spectral characteristic of intercepting light of wavelengths falling within the first wavelength band and transmitting light of wavelengths falling within a second wavelength band of longer wavelengths than the first wavelength band, and a second filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within a wavelength band that covers the second wavelength band and includes part of the first wavelength band and that is therefore wider than the second wavelength band including the wavelengths of the light transmitted by the first filter. At least the first filter is capable of being inserted into an optical path of the photography optical system and displaced therefrom. The camera also comprises a photography switch with which an operator gives instructions to photograph the fundus image as still images under strobe light, a controller for causing a strobe to produce the strobe light when the photography switch is pressed and the first filter is inserted into the optical path, and a display for displaying the fundus image produced by the photography optical system.
The illumination optical system includes an exciter filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within the first wavelength band and intercepting light of wavelengths falling within the second wavelength band, and that is displaceable from the optical path. In addition, for enabling observation, the controller causes the first filter to be displaced from the optical path and causes the second filter to be inserted thereinto, and for enabling photography, the controller causes the first filter to be inserted into the optical path. Also, the photography switch can comprise a double switch, and in this case, the controller controls insertion of the second filter in response to pressing of a first-step switch of the double switch, and controls flashing of the strobe light in response to pressing of a second-step switch thereof. Further, when the time interval between the pressing of the first-step switch and the pressing of the second-step switch is smaller than a predetermined value, the controller disables insertion of the second filter. Moreover, in one embodiment, the eye fundus camera enables fluorescence photography of an eye fundus with fluorescein, the first wavelength band includes wavelengths suitable for excitation of the fluorescein, and the second wavelength band includes wavelengths of light produced by fluorescence of the excited fluorescein.
According to another aspect, the present invention that achieves at least one of these objectives relates to an eye fundus camera comprising an illumination optical system for illuminating a fundus of a patient""s eye. The illumination optical system includes a first filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within a first wavelength band and intercepting light of wavelengths falling within a second wavelength band of longer wavelengths than the first wavelength band, and a second filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within a wavelength band which covers the first wavelength band and includes part of the second wavelength band and that is therefore wider than the first wavelength band including the wavelengths of the light transmitted by the first filter. At least the first filter is capable of being inserted into an optical path of the illumination optical system and displaced therefrom. The camera also comprises a photography optical system for forming an image of a fundus illuminated by the illumination optical system so that the fundus image will be produced by the photography optical system. The photography optical system including a third filter that exhibits a spectral characteristic of intercepting light of wavelengths falling within the first wavelength band and transmitting light of wavelengths falling within the second wavelength band. The camera also comprises a display for displaying the fundus image produced by the photography optical system.
The camera can also comprise a controller for enabling observation by causing the first filter to be displaced from the optical path and causing the second filter to be inserted into the optical path, and for enabling photography by causing the first filter to be inserted into the optical path. In addition, the camera can also comprise a photography switch with which an operator instructs the camera to photograph the fundus image as still images under strobe light, and a controller for, when the photography switch is pressed, causing a strobe to produce the strobe light with the first filter inserted into the optical path. The photography switch can comprise a double switch, and in this case, the controller causes the second filter to be inserted into the optical path in response to pressing of a first-step switch of the double switch, and causes the strobe to produce the strobe light in response to pressing of a second-step switch thereof. In one embodiment, the eye fundus camera enables fluorescence photography of a fundus with fluorescein, the first wavelength band includes wavelengths suitable for excitation of the fluorescein, and the second wavelength band includes wavelengths of light produced by the fluorescence of the excited fluorescein.
According to yet another aspect, the present invention that achieves at least one of these objective relates to an eye fundus infrared camera suitable for infrared fluorescence photography comprising an illumination optical system for illuminating a fundus of a patient""s eye with excitation light of wavelengths suitable to fluoresce fluorescein and a photography optical system for forming an image of the eye fundus illuminated by the illumination optical system so that a fundus image will be produced by the infrared camera. The photography optical system includes a first barrier filter that exhibits a spectral characteristic of intercepting the excitation light and transmitting light of wavelengths that are longer than the wavelengths of the excitation light produced by the fluorescence of fluorescein, and a second barrier filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within a wavelength band which covers the wavelengths of the light produced by the fluorescence of fluorescein and includes part of the wavelengths of the excitation light and which is therefore wider than the wavelength band including the wavelengths of the light produced by the fluorescence of fluorescein and being transmitted by the first barrier filter. At least the first barrier filter is capable of being inserted into the optical path of the photography optical system and displaced therefrom. The camera further comprises a photography switch with which an operator instructs the infrared camera to photograph the fundus image as still images under strobe light and a controller for causing, when the photography switch is pressed, a strobe to produce the strobe light with the first barrier filter inserted into the optical path. In addition, the camera comprises a display for displaying the fluorescence fundus image produced by the infrared camera.
According to yet another aspect, the present invention that achieves at least one of these objectives relates to an eye fundus infrared camera suitable for fluorescence photography comprising an illumination optical system for illuminating a fundus of a patient""s eye with excitation light of wavelengths suitable to fluoresce fluorescein. The illumination optical system includes a first exciter filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within a first wavelength band and intercepting light of wavelengths that are longer than the wavelengths of the first wavelength band produced by the fluorescence of fluorescein, and a second exciter filter that exhibits a spectral characteristic of transmitting light of wavelengths falling within a wavelength band which covers the wavelengths of the excitation light and includes part of the wavelengths of the light produced by the fluorescence of fluorescein and which is therefore wider than the first wavelength band including the wavelengths of the light transmitted by the first exciter filter. At least the first exciter filter is capable of being inserted into an optical path of the illumination optical system and displaced therefrom. The camera further comprises a photography optical system for forming an image of the fundus illuminated by the illumination optical system so that the fundus image will be produced by the infrared camera. The photography optical system includes a barrier filter that exhibits a spectral characteristic of intercepting the excitation light and transmitting the light produced by the fluorescence of fluorescein, and a display for displaying the fluorescence fundus image produced by the photography optical system. In one embodiment, the fluorescein is indocyanine green.
According to still another aspect, the present invention that achieves at least one of these objectives relates to a method of performing fluorescence photography of an eye fundus with an eye fundus camera comprising the steps of illuminating the fundus of a patient""s eye with light of wavelengths only falling within a first wavelength band, transmitting light reflected by the fundus only in a portion of the first wavelength band through a photography optical system to an infrared television camera to produce a fundus image, displaying the fundus image to permit an operator of the fundus camera to align and focus the fundus camera while viewing the displayed fundus image, measuring the time from injection of a fluorescein into the patient""s eye, the fluorescein fluorescing and producing light of wavelengths falling into a second wavelength band in response to being exposed to excitation light in the first wavelength band, transmitting light only in the second wavelength band from the patient""s eye produced by the fluorescing of the fluorescein through the photography optical system to the infrared television camera, and recording a motion picture of the fundus and displaying the fundus image produced by the infrared camera using the light only in the second wavelength band from the patient""s sys produced by the fluorescing of the fluorescein.
The illuminating step can comprise the step of inserting an exciter filter transmitting light of wavelengths only falling within a first wavelength band into the optical path of an illumination optical system. The first transmitting step can comprise the step of inserting a first barrier filter transmitting light only in the portion of the first wavelength band into the optical path of the photography optical system. The measuring step can be performed by starting a timer. The second transmitting step can comprise the step of removing the first barrier filter from the optical path of the photography optical system and inserting a second barrier filter transmitting light of wavelengths only in the second wavelength band into the optical path of the photography optical system.
In addition, the method can further comprise the steps of transmitting light reflected by the fundus only in the portion of the first wavelength band through a photography optical system to the infrared television camera to produce a fundus image using the first-wavelength-band light in response to the elapsing of a predetermined time from the time of injection of a fluorescein into the patient""s eye measured in the measuring step, displaying the fundus image produced using the first-wavelength-band light to permit an operator of the fundus camera to designate a region of the fundus to be photographed, transmitting light only in the second wavelength band from the patient""s eye produced by the fluorescing of the fluorescein through the photography optical system to the infrared television camera in response to a photography switch being pressed by the operator, stopping the illuminating step, flashing strobe light to illuminate the patient""s eye with strobe light, and recording still images of the strobe-illuminated fundus of the patient""s eye in response to a photography switch being pressed by the operator, stopping the measuring operation performed in the measuring step, and terminating the recording of still images in response to the stopping of the measuring operation in the measuring-operation stopping step.
Further, the transmitting step performed in response to the elapsing of the predetermined time is performed by displacing the second barrier filter out of the optical path of the photography optical system and inserting the first barrier filter into the optical path of the photography optical system. In addition, the transmitting step of transmitting light only in the second wavelength band in response to a photography switch being pressed by the operator is performed by displacing the first barrier filter out of the optical path of the photography optical system and inserting the second barrier filter into the optical path of the photography optical system.
In addition, the method can further comprise the steps of stopping the illuminating step, flashing strobe light to illuminate the patient""s eye with strobe light, and recording still images of the strobe-illuminated fundus of the patient""s eye in response to both a determination that a predetermined amount of time has not elapsed from the time of injection of a fluorescein into the patient""s eye measured in the measuring step and a photography switch being pressed by the operator.
According to still another aspect, the present invention that achieves at least one of these objectives relates to a method of performing fluorescence photography of an eye fundus with an eye fundus camera comprising the steps of illuminating the fundus of a patient""s eye with light of wavelengths only falling within a first wavelength band and a portion of a second wavelength band of longer wavelengths than the first wavelength band, transmitting light reflected by the fundus only in the portion of the second wavelength band from a photography optical system to an infrared television camera to produce a fundus image, displaying the fundus image to permit an operator of the fundus camera to align and focus the fundus camera while viewing the displayed fundus image, measuring the time from injection of a fluorescein into the patient""s eye, the fluorescein fluorescing and producing light of wavelengths falling into the second wavelength band in response to being exposed to excitation light in the first wavelength band, transmitting light only in the second wavelength band from the patient""s eye produced by the fluorescing of the fluorescein from the photography optical system to the infrared television camera, and recording a motion picture of the fundus and displaying the fundus image produced by the infrared camera using the light only in the second wavelength band from the patient""s eye produced by the fluorescing of the fluorescein.
The illuminating step comprises the step of inserting a first exciter filter transmitting light of wavelengths only falling within a first wavelength band and the portion of the second wavelength band into the optical path of an illumination optical system. The first transmitting step comprises the step of inserting a barrier filter transmitting light only in the second wavelength band into the optical path of the photography optical system. The measuring step is performed by starting a timer. The second transmitting step comprises the step of removing the first exciter filter from the optical path of the illumination optical system and inserting a second exciter filter transmitting light of wavelengths only in the first wavelength band into the optical path of the illumination optical system.
The method can further comprise the steps of transmitting light reflected by the fundus only in the portion of the second wavelength band from the photography optical system to the infrared television camera to produce a fundus image by using the light illuminating the fundus from the illumination optical system in response to the elapsing of a predetermined time from the time of injection of a fluorescein into the patient""s eye measured in the measuring step, displaying the fundus image produced by using the light illuminating the fundus from the illumination optical system to permit an operator of the fundus camera to designate a region of the fundus to be photographed, transmitting light only in the second wavelength band from the patient""s eye produced by the fluorescing of the fluorescein from the photography optical system to the infrared television camera in response to a photography switch being pressed by the operator, stopping the illuminating step, flashing strobe light to illuminate the patient""s eye with strobe light, and recording still images of the strobe-illuminated fundus of the patient""s eye in response to a photography switch being pressed by the operator, stopping the measuring operation performed in the measuring step and terminating the recording of still images in response to the stopping of the measuring operation in the measuring-operation stopping step.
The transmitting step performed in response to the elapsing of the predetermined time is performed by displacing the second exciter filter out of the optical path of the illumination optical system. The transmitting step of transmitting light only in the second wavelength band in response to a photography switch being pressed by the operator is performed by displacing the first exciter filter out of the optical path of the illumination optical system and inserting the second exciter filter into the optical path of the illumination optical system.
In addition, the method can further comprise the steps of stopping the illuminating step, flashing strobe light to illuminate the patient""s eye with strobe light, and recording still images of the strobe-illuminated fundus of the patient""s eye in response to both a determination that a predetermined amount of time has not elapsed from the time of injection of a fluorescein into the patient""s eye measured in the measuring step and a photography switch being pressed by the operator.
According to still another aspect, the present invention that achieves at least one of these objectives relates to an eye fundus camera comprising means for illuminating the fundus of a patient""s eye with light of wavelengths falling within a first wavelength band, means for forming an image of the fundus illuminated by the illuminating means and for photographing the image. The image forming means includes first filter means for intercepting light of wavelengths falling within the first wavelength band and transmitting light of wavelengths falling within a second wavelength band of longer wavelengths than the first wavelength band, and second filter means for transmitting light of wavelengths falling within a wavelength band that covers the second wavelength band and includes part of the first wavelength band and that is therefore wider than the second wavelength band including the wavelengths of the light transmitted by the first filter means. At least the first filter means is capable of being inserted into an optical path of the image forming means and displaced therefrom. The camera also comprises operator-actuated means for instructing the photographing of the fundus image with the image forming means as still images under strobe light, control means for controlling a strobe to produce the strobe light when the operator-actuated means is actuated and the first filter means is inserted into the optical path, and display means for displaying the fundus image produced by he image forming means.
The illuminating means includes exciter filter means for transmitting light of wavelengths falling within the first wavelength band and intercepting light of wavelengths falling within the second wavelength band, and that is displaceable from the optical path. For enabling observation, the control means controls the first filter means to be displaced from the optical path and controls the second filter means to be inserted thereinto. For enabling photography, the control means controls the first filter means to be inserted into the optical path. The operator-actuated means can comprise double instruction means for permitting the operator to input two different instructions into the camera. In this embodiment, the control means controls insertion of the second filter means in response to the operator actuating first instruction means of the double instruction means, and the control means controls flashing of the strobe light in response to the operator actuating second instruction means of the double insertion means. When the time interval between the actuating the first instruction means and actuating the second instruction means is smaller than a predetermined value, the control means disables insertion of the second filter means. In addition, in one embodiment, the eye fundus camera enables fluorescence photography of an eye fundus with fluorescein, the first wavelength band includes wavelengths suitable for excitation of the fluorescein, and the second wavelength band includes wavelengths of light produced by fluorescence of the excited fluorescein.
According to still another aspect, the present invention that achieves at least one of these objectives relates to an eye fundus camera comprising illuminating means for illuminating a fundus of a patient""s eye. The illuminating means includes first filter means for transmitting light of wavelengths falling within a first wavelength band and intercepting light of wavelengths falling within a second wavelength band of longer wavelengths than the first wavelength band, and second filter means for transmitting light of wavelengths falling within a wavelength band that covers the first wavelength band and includes part of the second wavelength band and that is therefore wider than the first wavelength band including the wavelengths of the light transmitted by the first filter means. At least the first filter means is capable of being inserted into an optical path of the illuminating means and displaced therefrom. The camera also comprises means for forming an image of a fundus illuminated by the illuminating means and photographing the fundus image. The image forming means includes third filter means for intercepting light of wavelengths falling within the first wavelength band and transmitting light of wavelengths falling within the second wavelength band, and display means for displaying the fundus image produced by the image forming means.
The camera can further comprise control means for enabling observation by controlling the first filter means to be displaced from the optical path and controlling the second filter means to be inserted into the optical path, and for enabling photography by controlling the first filter means to be inserted into the optical path. In addition, the camera can further comprise operator-actuated means for instructing the camera to photograph the fundus image as still images under strobe light, and control means for, when the operator-actuated means is actuated by the operator, controlling a strobe to produce the strobe light with the first filter means inserted into the optical path. The operator-actuated means comprises double instruction means for permitting the operator to input two different instructions into the camera. In this embodiment, the control means controls the second filter means to be inserted into the optical path in response to the operator actuating first instruction means of the double instruction means, and controls the strobe to produce the strobe light in response to the operator actuating second instruction means of the double instruction means. In addition, the eye fundus camera enables fluorescence photography of a fundus with fluorescein, the first wavelength band includes wavelengths suitable for excitation of the fluorescein, and the second wavelength band includes wavelengths of light produced by the fluorescence of the excited fluorescein.
According to yet another aspect, the present invention that achieves at least one of these objectives relates to an eye fundus infrared camera suitable for infrared fluorescence photography comprising illuminating means for illuminating a fundus of a patient""s eye with excitation light of wavelengths suitable to fluoresce fluorescein, and means for forming an image of the eye fundus illuminated by the illuminating means and photographing the fundus image. The image forming means includes first barrier filter means for intercepting the excitation light and transmitting light of wavelengths that are longer than the wavelengths of the excitation light produced by the fluorescence of fluorescein, and second barrier filter means for transmitting light of wavelengths falling within a wavelength band which covers the wavelengths of the light produced by the fluorescence of fluorescein and includes part of the wavelengths of the excitation light and which is therefore wider than the wavelength band including the wavelengths of the light produced by the fluorescence of fluorescein and being transmitted by the first barrier filter means. At least the first barrier filter means is capable of being inserted into the optical path of the photography optical system and displaced therefrom. The camera also includes operator-actuated means for instructing the photographing of the fundus image with the image forming means as still images under strobe light, control means for causing, when the operator-actuated means is actuated, a strobe to produce the strobe light with the first barrier filter means inserted into the optical path, and display means for displaying the fluorescence fundus image produced by the infrared camera.
According to still another aspect, the present invention that achieved at least one of these objectives relates to an eye fundus infrared camera suitable for fluorescence photography comprising illuminating means for illuminating a fundus of a patient""s eye with-excitation light of wavelengths suitable to fluoresce fluorescein. The illuminating means includes first exciter filter means for transmitting light of wavelengths falling within a first wavelength band and intercepting light of wavelengths that are longer than the wavelengths of the first wavelength band produced by the fluorescence of fluorescein, and second exciter filter means for transmitting light of wavelengths falling within a wavelength band that covers the wavelengths of the excitation light and includes part of the wavelengths of the light produced by the fluorescence of fluorescein and that is therefore wider than the first wavelength band including the wavelengths of the light transmitted by the first exciter filter means. At least the first exciter filter means is capable of being inserted into an optical path of the illuminating means and displaced therefrom. The camera also comprises means for forming an image of the fundus illuminated by the illuminating means and photographing the fundus image. The image forming means includes barrier filter means for intercepting the excitation light and transmitting the light produced by the fluorescence of fluorescein, and display means for displaying the fluorescence fundus image produced by the image forming means. In one embodiment, the fluorescein is indocyanine green.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.